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Effectiveness of malaria control in Eritrea, 1996 to 2003

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Effectiveness of malaria control in Eritrea, 1996 to 2003

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    1. Effectiveness of malaria control in Eritrea, 1996 to 2003 Patricia M Graves June 6, 2008 IRI

    2. Eritrea History Eritrea: Former Italian colony since 1890. Became British protectorate in 1941. From the point of view of justice, the opinions of the Eritrean people must receive consideration. Nevertheless, the strategic interests of the United States in the Red Sea Basin and considerations of security and world peace make it necessary that the country (Eritrea) has to be linked with our ally, Ethiopia", John Foster Dulles in 1952. Under UN mandate, Federated with Ethiopia in 1952. Struggle for independence started 1961. Annexed by Ethiopia in 1962. Liberated in 1991, officially in 1993 after referendum. Border still disputed. War from May 1998 to 2000 over this. Ethiopia –never colonised. Invaded by Italy in 1896 but defeated at battle of Adua Invaded by Italy in 1935 but defeated in 1941 1974 revolution overthrew Haile Selassie Derg regime overthrown 1991. History Eritrea: Former Italian colony since 1890. Became British protectorate in 1941. From the point of view of justice, the opinions of the Eritrean people must receive consideration. Nevertheless, the strategic interests of the United States in the Red Sea Basin and considerations of security and world peace make it necessary that the country (Eritrea) has to be linked with our ally, Ethiopia", John Foster Dulles in 1952. Under UN mandate, Federated with Ethiopia in 1952. Struggle for independence started 1961. Annexed by Ethiopia in 1962. Liberated in 1991, officially in 1993 after referendum. Border still disputed. War from May 1998 to 2000 over this. Ethiopia –never colonised. Invaded by Italy in 1896 but defeated at battle of Adua Invaded by Italy in 1935 but defeated in 1941 1974 revolution overthrew Haile Selassie Derg regime overthrown 1991.

    3. Eritrea – malaria prevalence survey 2002

    4. 1a: Eritrea – malaria situation Reported clinical malaria cases by age-group, Eritrea 1996 to 2003

    5. Eritrea rainfall trend 1996 to 2003

    6. Eritrea – all diagnoses

    8. Eritrea – zones and subzones

    9. Eritrea – zones and subzones

    10. Routine surveillance data Can assist in: Monitoring trends Clarifying and measuring seasonality Prioritizing areas for intervention Defining and quantifying epidemics Evaluating control measures

    11. Source of cases dataset 325 health facilities (1 to 9 per subzone) Excluded: National referral hospitals Specialty clinics (ophthalmic and MCH) Non-functioning facilities (no reports) Private doctors Worksite clinics Remaining: 243 health facilities representing all subzones.

    12. Eritrea: Reporting rate

    13. Focus on reported outpatient clinical malaria cases Few facilities had diagnostics at start of period Diagnostic capacity increased during study Too few deaths and inpatients Seasonal patterns clearly seen in clinical malaria cases Inconsistency in lab forms for Pf/Pv.

    14. Eritrea – malaria cases by month, 1996 to 2003

    18. Data sources used to analyze effectiveness of interventions Datasets for 96 months (1998 to 2003), 58 subzones (districts) Outpatient clinical malaria cases by month from new NHMIS (restricted here from 325 to 242 health facilities). Satellite-derived rainfall (CPC CMAP 0407) and NDVI (version e from USGS/ADDS), averaged over subzone. Amounts of interventions applied (IRS, ITNs, larval control)

    19. Intervention data collected by subzone and month Residual spraying (amount of chemical, people covered) Number of impregnated nets issued and reimpregnated Number of larval habitats eliminated Chemical larviciding (number of sites, amount of chemical) Treatments given by village health agents

    20. Eritrea 1998 to 2003

    21. Eritrea 1998 to 2003

    22. Eritrea – 1998 to 2003

    23. Eritrea NDVI trend 1996 to 2003

    24. Analysis Outcome variable: number of clinical cases by subzone and month. Cross-sectional multivariate time-series regression/ Poisson regression First tested for ‘endogeneity’ (i.e. control being done in response to climate or increased case numbers) – no consistent pattern. Independent variables expressed as ‘anomalies’ (deviations from subzone/calendar month means) to adjust for seasonality Subzone fixed effect variables Depreciation/cumulation of insecticides and nets Climate variables as aggregated lags (Rain 2-3 months; NDVI 0-1 month.

    25. Positive relationships between climate variables and malaria cases (Anseba and Gash Barka)

    26. Negative relationships between intervention variables and malaria cases

    27. Eritrea analysis conclusions Reduction in cases in Eritrea from 1998 to 2003 was not solely due to climate shifts. Both IRS (with DDT or malathion) in one zone, and ITNs in two zones, were independently associated with reduction in cases. There was evidence of effectiveness of larval control in one zone. Better monitoring of interventions, especially larval control, is needed. Routine malaria surveillance data (despite known drawbacks) is useful for evaluating the effectiveness of control measures, as long as climate variation is taken into account.

    28. Thank you!

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